British Pat. No. 2,047,133 shows a tool change apparatus comprising a tool, a storage device having means for releasably supporting the tool in a stored position, a head which is capable of movement relative to the storage device for removal of the tool from the stored position and return of the tool thereto, the head having an axis and including first support surfaces arranged at a plane transverse to said axis, the tool having second support surfaces engageable with the first support surfaces, the first and second support surfaces being adapted to define a kinematic support, and operating means for engaging the tool with the head at said support surfaces and disengaging the tool therefrom. In the known apparatus the engagement and disengagement between the head and the tool is effected by a bayonet system involving relative rotation between the head and the tool about said axis. This leads to difficulty for example in cases where electrical contacts need to be provided between the head and the tool because such contacts would confront each other in the direction of said axis so that said rotation could be undesirable.